Ground-mounting away from the village allows the PV arrays to receive full sunlight and allows each home in the Ecovillage to receive equal portions of credit for the energy.

Tricky roofs and lack of individual ownership can complicate adding a PV system to multifamily buildings.

The EKM meters monitor the electricity consumption of each residence.

One of two power walls, which include performance metering, disconnects, the inverters, and the members’ consumption meters.

The second power wall. Each power wall holds the inverters for two of the neighborhood quadrants, with one set of AC outputs going underground to feed the remote quadrant.

The Sunny WebBox is the communications hub between the inverter data and the Internet, so that users have online access to monitor the PV system remotely.

Residents celebrate the new 50 kW PV system.

Beginner

After Construction

With the array complete and our new metering system in place, we set up the billing system. Previously, our residents all were billed at a residential rate, but by combining meters, our only option was to convert our account to commercial. We negotiated the service rate classification for the new master meters with the utility and we got the state public service commission involved as well. We contended that since the load was still all residential usage that we should be able to retain a residential (nondemand charge) tariff. However, New York’s PSC regulations do not include a multifamiliy residential tariff (nor any time-of-use classes, except for large industrial customers), so we ended up on “SC2,” a basic commercial tariff with demand charges.

This was not a big price difference, but it did require paying an additional monthly fee known as a demand charge, which reflects how quickly you draw power from the grid, in addition to how much you draw. It’s as if you were charged for how hard you stomped on your car’s gas pedal in addition to having to pay for the gas you use. In our case, demand charge is measured as the highest-drawing 15-minute period during the billing period on each of the four master meters. For example, in January and February 2012, the highest demand was 61 kW across all four quadrants, and at a fee of $8.13 per kW the total charge was about $495. The overall bill for that period (including demand) was $1,327. Despite that big demand charge, it turned out that because some other charges (such as the delivery fee) are cheaper on the SC2 tariff, it only cost about 4% more. And we could have dropped that even lower had we done a better job managing our demand.

That gave us an economic incentive to minimize avoidable energy use during times of peak simultaneous usage, such as during normal meal times. Our smart-metering system gives residents the tools to examine their use and consider rescheduling things like dishwasher loads to be outside of the peak periods. Residents have been changing their energy habits, and even initiated discussion groups to share energy-saving strategies, such as using pressure cookers and slow cookers to decrease electric stove use.

Calculating monthly bills turned out to be more complex than we originally anticipated. Utility bills contain a bewildering number of separate charges, and we wanted to ensure that costs were being passed on fairly for both light and heavy electricity users. Our solution was to classify each of the various charges on the utility bill into categories of fixed, per-kWh, and demand charges, and apportion them to residents. Once these ratios/percentages were figured, we built a spreadsheet to automatically calculate charges for individual households.

The electricity generated by the PV system is divided evenly among the 30 households, giving each a kWh credit. This provides a target to see how close each household can get to “net zero” electricity usage. For the energy-thriftiest households, that sometimes results in having no monthly charge for electricity.

Lessons Learned

The most important thing we learned from this project is the value of steadiness—to neither rush nor allow ourselves to be deterred. At every point, there were obstacles, surprises, and things we didn’t know how to do. Cultivating an attitude of relaxed determination kept us on track, and made the project satisfying.

We also became acutely aware of the ways public policy can impact the development of renewable energy. While our project was helped immensely by the generous incentives from state and federal agencies, we also had a lot of complications that would be unnecessary with some common-sense changes to law and regulatory policy.

For example, our array was actually situated only 50 feet from our site’s main utility feed. It would have been convenient and cost-effective to connect the array there, if we could have gotten a fair price for the power produced. Instead, since the only way to get a good price for PV power is to do net metering against a load served by a single utility meter, we had to trench more than 500 feet and rework our entire metering system. That added complexity to our project and up to 30% of its cost. A few simple policy changes could greatly facilitate the expansion of PV deployment (see “Changes to Public PV Policy” sidebar).